Ureidoalkanoylaminocarbonyl amino and imino acids and esters

ABSTRACT

Compounds of the formula ##STR1## are disclosed. These compounds are useful as hypotensive agents due to their angiotensin converting enzyme inhibition activity and depending upon the definintion of X may also be useful as analgesics due to their enkephalinase inhibition activity.

This is a division of application Ser. No. 726,264, filed Apr. 22, 1985now U.S. Pat. No. 4,740,508.

BACKGROUND OF THE INVENTION

Natarajan et al. in Australian patent application No. 17,203 discloseacylalkylaminocarbonyl substituted amino and imino acid compounds of theformula ##STR2## wherein R₂ is certain aryl, aralkyl, heterocyclo, oralkylene-heterocyclo groups. These compounds possess angiotensinconverting enzyme inhibition activity and enkephalinase inhibitionactivity depending upon the definition of X.

Almquist et al. in U.S. Pat. No. 4,329,473 disclose angiotensinconverting enzyme inhibiting compounds of the formula ##STR3## whereinR₂ is aryl, alkyl, alkoxy or benzyloxy.

SUMMARY OF THE INVENTION

This invention is directed to novel compounds of the formula ##STR4## Ris hydrogen, lower alkyl, halo substituted lower alkyl, --(CH₂)_(m)--cycloalkyl, ##STR5## v is an integer from 2 to 6. R₁ and R₂ areindependently selected from hydrogen, lower alkyl, halo substitutedlower alkyl, --(CH₂)_(m) --cycloalkyl, ##STR6## or R₁ and R₂ taken withthe N atom form a heterocyclo ring of the formula ##STR7## R₂₆ ishydrogen or lower alkyl. X is an amino or imino acid or ester of theformula ##STR8## n is zero, one or two. R₂₅ is lower alkyl of 1 to 4carbons or ##STR9## R₇ is hydrogen, lower alkyl, halogen, hydroxy,##STR10## a 1- or 2-naphthyl of the formula ##STR11## a substituted 1-or 2-naphthyl of the formula ##STR12## a 1- or 2-naphthyloxy of theformula ##STR13## a substituted 1- or 2-naphthyloxy of the formula##STR14## a 1- or 2-naphthylthio of the formula ##STR15## or asubstituted 1- or 2-naphthylthio of the formula ##STR16## R₈ is halogen,##STR17## -O-lower alkyl, a 1- or 2-naphthyloxy of the formula ##STR18##a substituted 1- or 2-naphthyloxy of the formula ##STR19## a 1- or2-naphthylthio of the formula ##STR20## or a substituted 1- or2-naphthylthio of the formula ##STR21## R₉ is keto, ##STR22## R₁₀ ishalogen or --Y--R₁₆ . R₁₁, R'₁₁, R₁₂ and R'₁₂ are independently selectedfrom hydrogen and lower alkyl or R'₁₁, R₁₂ and R'₁₂ are hydrogen and R₁₁is ##STR23## R₁₃ is lower alkyl of 1 to 4 carbons, lower alkoxy of 1 to4 carbons, lower alkylthio of 1 to 4 carbons, chloro, bromo, fluoro,trifluoromethyl, hydroxy, phenyl, phenoxy, phenylthio, or phenylmethyl.

R₁₄ is lower alkyl of 1 to 4 carbons, lower alkoxy of 1 to 4 carbons,lower alkylthio of 1 to 4 carbons, chloro, bromo, fluoro,trifluoromethyl or hydroxy.

m is zero, one, two, three, or four.

p is one, two or three provided that p is more than one only if R₁₃ orR₁₄ is methyl, methoxy, chloro, or fluoro.

R₁₅ is hydrogen or lower alkyl of 1 to 4 carbons.

Y is oxygen or sulfur.

R₁₆ is lower alkyl of 1 to 4 carbons, ##STR24## or the R₁₆ groups jointo complete an unsubstituted 5- or 6-membered ring or said ring in whichone or more of the carbons has a lower alkyl of 1 to 4 carbons or adi(lower alkyl of 1 to 4 carbons) substituent.

R₄ is hydrogen, lower alkyl, ##STR25## R₅ is hydrogen, lower alkyl,##STR26## r is an integer form 1 to 4 R₁₉ is lower alkyl, benzyl orphenethyl.

R₂₀ is hydrogen, lower alkyl, benzyl or phenethyl.

R₃ is hydrogen, lower alkyl, ##STR27## halo substituted lower alkyl,--(CH₂)_(m) --cycloalkyl, ##STR28## wherein m, R₁₄, p and r are asdefined above. R₆ is hydrogen, lower alkyl, benzyl, benzhydryl,##STR29## or a salt forming ion. R₁₇ is hydrogen, lower alkyl,cycloalkyl, or phenyl.

R₁₈ is hydrogen, lower alkyl, lower alkoxy or phenyl.

R₂₁ and R₂₂ are independently selected from hydrogen and lower alkyl.

R₂₃ is lower alkyl.

R₂₄ is hydrogen, lower alkyl, ##STR30##

DETAILED DESCRIPTION OF THE INVENTION

This invention in its broadest aspects relates to the amino and iminoacid and ester compounds of formula I and to compositons and the methodof using such compounds as pharmaceutical agents.

The term lower alkyl used in defining various symbols refers to straightor branched chain radicals having up to seven carbons. The preferredlower alkyl groups are up to four carbons with methyl and ethyl mostpreferred. Similarly the terms lower alkoxy and lower alkylthio refer tosuch lower alkyl groups attached to an oxygen or sulfur.

The term cycloalkyl refers to saturated rings of 4 to 7 carbon atomswith cyclopentyl and cyclohexyl being most preferred.

The term halogen refers to chloro, bromo and fluoro. The term halosubstituted lower alkyl refers to such alkyl groups in which one or morecarbons have been replaced by a halogen, i.e., CF₃, CH₂ Cl₃, CH₂ Br,etc.

The symbols ##STR31## represent that the alkylene bridge is attached toan available carbon atom.

The compounds of formula I are obtained by treating an amine of theformula ##STR32## particularly the hydrochloride salt thereof, whereinR₆ in the definition of X is an easily removable protecting group suchas benzyl, benzhydryl, t-butyl, etc., with p-nitrophenyl chloroformateor phosgene in the presence of N-methylmorpholine followed by treatmentwith an amine of the formula ##STR33## Alternatively, the amine offormula III could first be treated with p-nitrophenyl chloroformate orphosgene and the resultant product then treated with the aminointermediate of formula II.

The compounds of formula I wherein R₁ and R₂ are both hydrogen can beprepared by employing ammonia as the reagent of formula III in the firstprocedure described above.

Removal of the R₆ protecting group, for example by hydrogenation when R₆is benzyl, yields the acid products of formula I, i.e., R₆ is hydrogen.

The amino intermediate of formula II can be prepared as follows. Anamino acid derivative of the formula ##STR34## wherein R₃₀ is t-butyl,--CH₂ --CCl₃, benzhydryl, ##STR35## or --(CH₂)₂ --Si(CH₃)₃ is treatedsequentially with isobutylchloroformate and a tertiary base such asN-methylmorpholine followed by reaction with diazomethane and treatmentwith hydrogen chloride to give ##STR36## The chloride of formula V istreated with a substituted benzylamine of the formula ##STR37## to give##STR38## Removal of the benzyl protecting group, for example, byhydrogenation gives ##STR39##

The amine of formula VIII, particularly the p-toluenesulfonic acid saltthereof, is treated with the chlorocarbonylamine of the formula##STR40## in the presence of a base such as triethylamine, wherein R₆ inthe definition of X is an easily removable protecting group, followed byremoval of the t-butyl, benzhydryl, --CH₂ --CCl₃, --CH₂)₂ --Si(CH₃)₃, or##STR41## R₃₀ group, for example by treating with hydrogen chloride whenR₃₀ is t-butyl, to yield the amino intermediate of formula II.

In the above reactions, if R is hydrogen then the N-atom is protected,for example by a t-butoxycarbonyl group which can be removed byhydrogenation following completion of the reaction. Also, if R₂₆ ishydrogen then that N-atom is protected, for example, by abenzyloxycarbonyl group which can be removed following completion of thereaction. Similarly, if any or all of R, R₁, R₂, R₃ and R₅ are ##STR42##then the hydroxyl, amino, imidazolyl, mercaptan or guanidinyl functionshould be protected during the reaction. Suitable protecting groupsinclude benzyloxycarbonyl, t-butoxycarbonyl, benzyl,trimethylsilylethylcarbonyl, benzhydryl, trityl, etc., and nitro in thecase of guanidinyl. The protecting group is removed by hydrogenation,treatment with acid, or other known methods following completion of thereaction.

The ester products of formula I wherein R₆ is ##STR43## may be obtainedby employing the amino or imino acid ester of formula III in the abovereactions with such ester group already in place.

The ester products of formula I wherein R₆ is ##STR44## can also beobtained by treating the product of formula I wherein R₆ is hydrogenwith a molar excess of the compound of the formula ##STR45## wherein Lis a leaving group such as chlorine, bromine, tolylsulfonyl, etc.

The ester products of formula I wherein R₆ is ##STR46## can be preparedby treating the product of formula I wherein R₆ is hydrogen with a molarexcess of the compound of the formula ##STR47##

The ester products of formula I wherein R₆ is ##STR48## can be preparedby coupling the product of formula I wherein R₆ is hydrogen with a molarexcess of the compound of the formula ##STR49## or the formula ##STR50##in the presence of a coupling agent such as dicyclohexylcarbodiimide andthe optional presence of a catalyst such as dimethylaminopyridinefollowed by removal of the hydroxyl protecting group.

Similarly, the ester products of formula I wherein R₆ is ##STR51## canbe prepared by coupling the product of formula I wherein R₆ is hydrogenwith a molar excess of the compound of formula

    HO--CH.sub.2 --CH.sub.2 --N--(CH.sub.3).sub.2              (XIV)

or the formula ##STR52## in the presence of a coupling agent such asdicylohexylcarbodiimide and the optional presence of a catalyst such asdimethylaminopyridine.

The products of formula I wherein R₇ is amino may be obtained byreducing the corresponding products of formula I wherein R₇ is azido.

Preferred compounds of this invention are those of formula I wherein:

X is ##STR53## R₆ is hydrogen, straight or branched chain lower alkyl of1 to 4 carbons, or an alkali metal salt ion.

R₄ is cyclohexyl or phenyl and R₅ is hydrogen.

R₄ is hydrogen and R₅ is methyl, ##STR54## R₇ is hydrogen, cyclohexyl,lower alkoxy of 1 to 4 carbons, ##STR55## R₁₃ is methyl, methoxy,methylthio, Cl, Br, F, or hydroxy. m is zero, one or two.

t is two or three.

R is straight or branched chain lower alkyl of 1 to 4 carbons.

R₁ and R₂ are independently selected from straight or branched chainlower alkyl of 1 to 4 carbons or R₁ is cyclohexyl and R₂ is hydrogen orR₁ and R₂ taken together with the N atom to which they are attachedcomplete a heterocyclo ring of the formula ##STR56## wherein R₂₆ ishydrogen or straight or branched chain lower alkyl of 1 to 4 carbons.

R₃ is straight or branched chain lower alkyl of 1 to 4 carbons,##STR57## R₁₄ is methyl, methoxy, methylthio, Cl, Br, F, or hydroxy.

Most preferred compounds of this invention are those of formula Iwherein:

X is ##STR58## R is methyl. R₆ is hydrogen or an alkali metal salt ion.

R₁ and R₂ are each methyl or R₁ is cyclohexyl and R₂ is hydrogen or R₁and R₂ taken together with the N atom to which they are attachedcomplete a heterocyclo ring of the formula ##STR59##

The compounds of formula I wherein R₆ is hydrogen form salts with avariety of inorganic or organic bases. The nontoxic, pharmaceuticallyacceptable salts are preferred, although other salts are also useful inisolating or purifying the product. Such pharmaceutically acceptablesalts include alkali metal salts such as sodium, potassium or lithium,alkaline earth metal salts such as calcium, or magnesium, and saltsderived from amino acids such as arginine, lysine, etc. The salts areobtained by reacting the acid form of the compound with an equivalent ofthe base supplying the desired ion in a medium in which the saltprecipitates or in aqueous medium and then lyophilizing.

The compounds of formula I when R₃ is other than hydrogen contain anasymmetric center as represented by the * in formula I. Thus, thecompounds of formula I can exist in diastereomeric forms or in mixturesthereof. The above described processes can utilize racemates,enantiomers or diastereomers as starting materials. When diastereomericproducts are prepared, they can be separated by conventionalchromatographic or fractional crystallization methods.

The products of formula I wherein the imino acid ring is monosubstitutedgive rise to cis-trans isomerism. The configuration of the final productwill depend upon the configuration of the R₇, R₈ and R₉ substituent inthe starting material of formula III.

The compounds of formula I, and the pharmaceutically acceptable saltsthereof, are hypotensive agents. They inhibit the conversion of thedecapeptide angiotensin I to angiotensin II and, therefore, are usefulin reducing or relieving angiotensin related hypertension. The action ofthe enzyme renin on angiotensinogen, a pseudoglobulin in blood plasma,produces angiotensin I. Angiotensin I is converted by angiotensinconverting enzyme (ACE) to angiotensin II. The latter is an activepressor substance which has been implicated as the causative agent inseveral forms of hypertension in various mammalian species, e.g.,humans. The compounds of this invention intervene in theangiotensinogen→(renin)→angiotensin I→angiotensin II sequence byinhibiting angiotensin converting enzyme and reducing or eliminating theformation of the pressor substance angiotensin II. Thus by theadministration of a composition containing one (or a combination) of thecompounds of this invention, angiotensin dependent hypertension in aspecies of mammal (e.g., humans) suffering therefrom is alleviated. Asingle dose, or preferably two to four divided daily doses, provided ona basis of about 0.1 to 100 mg., preferably about 1 to 50 mg., per kg.of body weight per day is appropriate to reduce blood pressure. Thesubstance is preferably administered orally but parenteral routes suchas the subcutaneous, intramuscular, intravenous or intraperitonealroutes can also be employed.

The compounds of this invention can also be formulated in combinationwith a diuretic for the treatment of hypertension. A combination productcomprising a compound of this invention and a diuretic can beadministered in an effective amount which comprises a total daily dosageof about 30 to 600 mg., preferably about 30 to 330 mg. of a compound ofthis invention, and about 15 to 300 mg., preferably about 15 to 200 mg.of the diuretic, to a mammalian species in need thereof. Exemplary ofthe diuretics contemplated for use in combination of this invention arethe thiazide diuretics, e.g., chlorothiazide, hydrochlorothiazide,flumethiazide, hydroflumethiazide, bendroflumethiazide,methyclothiazide, trichloromethiazide, polythiazide or benzthiazide aswell as ethacrynic acid, ticrynafen, chlorthalidone, furosemide,musolimine, bumetanide, triamterene, amiloride and spironolactone andsalts of such compounds.

The compounds of formula I can be formulated for use in the reduction ofblood pressure in compositions such as tablets, capsules or elixirs fororal administration, or in sterile solutions or suspensions forparenteral administration. About 10 to 500 mg. of a compound of formulaI is compounded with physiologically acceptable vehicle, carrier,excipient, binder, preservative, stabilizer, flavor, etc., in a unitdosage form as called for by accepted pharmaceutical practice. Theamount of active substance in these compositions or preparations is suchthat a suitable dosage in the range indicated is obtained.

The compounds of formula I wherein X is ##STR60## also possessenkephalinase inhibition activity and are useful as analgesic agents.Thus, by the administration of a composition containing one or acombination of such compounds of formula I or a pharmaceuticallyacceptable salt thereof, pain is alleviated in the mammalian host. Asingle dose, or preferably two to four divided daily doses, provided ona basis of about 0.1 to about 100 mg. per kilogram of body weight perday, preferably about 1 to about 50 mg. per kilogram per day, producesthe desired analgesic activity. The composition is preferablyadministered orally but parenteral routes such as subcutaneous can alsobe employed.

The following examples are illustrative of the invention. Temperaturesare given in degrees centigrade.

EXAMPLE 11-[[Methyl[(S)-2-oxo-4-phenyl-3-[(1-piperidinylcarbonyl)amino]butyl]amino]carbonyl]-L-proline(a) (S)-[3-Chloro-2-oxo-1-(phenylmethyl)propyl]carbamic acid,1,1-dimethylethyl ester

To a stirred solution ofN-[(1,1-dimethylethoxy)carbonyl]-L-phenylalanine (26.5 g., 100 mmole) intetrahydrofuran (150 ml.) at -20° is added isobutylchloroformate (13ml., 100 mmole). N-Methylmorpholine (11 ml., 100 mmole) is then added indrops. The solution is stirred between -15° C. and -20° C. for fifteenminutes and then filtered. Tetrahydrofuran (25 ml.) is used for thewashings. The filtrate is added to a cold (ice bath) ethereal solutionof diazomethane in drops. After the addition is over, the ice bath isremoved, and the reaction mixture is stirred at ambient temperature for2 hours. Nitrogen is blown over the solution and the volume is reducedto 400 ml. The reaction mixture is then stirred in an ice bath andhydrogen chloride in acetic acid (2N, 55 ml.) is added in drops. Afterthe addition is over, the ice bath is removed and the reaction mixtureis stirred for 15 minutes at room temperature. The reaction mixture isevaporated in vacuo and the residue on attempted dissolution in etheraffords 6.2 g. of (S)-[3-chloro-2-oxo-1-(phenylmethyl)propyl]carbamicacid, 1,1-dimethylethyl ester; m.p. 104°-105°; [α]_(D) ²² =+20.3° (c=2,chloroform). The mother liquor on concentration and aftercrystallization from ether/hexane gives an additonal 17.65 g. ofproduct.

(b)(S)-[3-[Methyl(phenylmethyl)amino]-2-oxo-1-(phenylmethyl)propyl]carbamicacid, 1,1-dimethylethyl ester, p-toluenesulfonate salt

A solution of (S)-[3-chloro-2-oxo-1-(phenylmethyl)propyl]carbamic acid,1,1-dimethylethyl ester (6.43 g., 21.6 mmole), sodium bicarbonate (2.17g., 25.9 mmole), sodium iodide (1.62 g., 11.0 mmole) andbenzylmethylamine (2.76 ml., 2.14 mmole) in dimethylformamide (60 ml.)is stirred at room temperature for 4 hours. The resulting solution isconcentrated and partitioned between ether and water. The ether layer iswashed with water (twice) and extracted with 1N hydrochloric acid (fivetimes). The combined extracts are made basic using sodium bicarbonateand extracted with ethyl acetate. The ethyl acetate extracts are dried(MgSO₄) and concentrated. The crude crystalline residue is dissolved inether and a solution of p-toluenesulfonic acid (3.0 g., 28 mmole) inethyl acetate is added. The resulting pink crystals are triturated withhot ethyl acetate and collected to give 6.5 g. of(S)-[3-[methyl(phenylmethyl)amino]-2-oxo-1-(phenylmethyl)propyl]carbamicacid, 1,1-dimethylethyl ester, p-toluenesulfonate salt as a white solid;m.p. 150°-152°.

(c) (S)-[3-(Methylamino)-2-oxo-1-(phenylmethyl)propyl]carbamic acid,1,1-dimethylethyl ester, hydrochloride salt

A mixture of the p-toluenesulfonate salt product from part (b) (6.5 g.,11.7 mmole) and palladium hydroxide (20%) in methanol is hydrogenated atatmospheric pressure and room temperature for 1.5 hours. The resultingsolution is filtered, concentrated, and triturated with ether to give4.75 g. of a white crystalline solid. A portion of this material ispartitioned between ethyl acetate and 10% sodium bicarbonate. Theorganic layer is treated with hydrochloric acid/ether to give the crudehydrochloride salt as blue-green solid. Recrystallization frommethanol/ether gives(S)-[3-(methylamino)-2-oxo-1-(phenylmethyl)propyl]carbamic acid,1,1-dimethylethyl ester, hydrochloride salt; m.p. 164°-169°.

(d)1-[[[(S)-3-[[(1,1-Dimethylethoxy)carbonyl]amino]-2-oxo-4-phenylbutyl]methylamino]carbonyl]L-proline,phenylmethyl ester

N-Methylmorpholine (0.46 ml., 4.2 mmole) is added to a stirringsuspension of L-proline, phenylmethyl ester, hydrochloride salt (0.39g., 1.6 mmole) in methylene chloride (dry, distilled) at -40° followedby phosgene in benzene (approximately 1M, 2.5 ml., 2.5 mmole). Themixture is stirred at -30° for one hour. The ice bath is removed and themixture is stirred for an additional hour. The mixture is thenconcentrated in vacuo and diluted with methylene chloride.(S)-[3-(Methylamino)-2l -oxo-1-(phenylmethyl)propyl]carbamic acid,1,1-dimethylethyl ester, hydrochloride salt (0.34 g., 1.0 mmole) isadded to the solution and the mixture is stirred overnight. Theresulting solution is diluted with methylene chloride and washed with 1Nhydrochloric acid and 10% sodium bicarbonate, dried (MgSO₄) andconcentrated. The crude product (0.61 g.) is combined with material froma previous run (0.56 g.) and chromatographed on LPS-1 silica gel usinghexane:ethyl acetate (2:1) as the eluant. The combined fractions arerechromatographed on LPS-1 using ether:ethyl acetate (10:1) as eluent.Fractions containing the desired product (R_(f) =0.43, hexane:ethylacetate, 1:1) are combined and concentrated to give 0.26 g. of1-[[[(S)-3-[[(1,1-dimethylethoxy)carbonyl]amino]-2-oxo-4-phenylbutyl]methylamino]carbonyl]-L-proline,phenylmethyl ester.

(e)1-[[[(S)-3-Amino-2-oxo-4-phenylbutyl]methylamino]carbonyl]-L-proline,phenylmethyl ester

A solution of1-[[[(S)-3-[[(1,1-dimethylethoxy)carbonyl]amino]-2-oxo-4-phenylbutyl]methylamino]carbonyl]-L-proline,phenylmethyl ester (7.12 g., 13.6 mmole) is stirred in a saturatedsolution of hydrochloric acid/ethyl acetate for one hour. The resultingprecipitate is collected and washed with ethyl acetate to give 5.63 g.of 1-[[[(S)-3-amino-2-oxo-4-phenylbutyl]methylamino]carbonyl]-L-proline,phenylmethyl ester; m.p. 174°-175°; [α]_(D) ²⁵ =+16.20°. TLC (silicagel; chloroform:methanol:acetic acid, 4:1:1) R_(f) =0.60.

(f)1-[[[(S)-3-[[(4-Nitrophenoxy)carbonyl]amino]2-oxo-4-phenylbutyl]methylamino]carbonyl]-L-proline,phenylmethyl ester

N-Methylmorpholine (2.0 ml., 18.0 mmole) is added over a period of 5minutes to a cooled (-30°) mixture of1-[[[(S)-3-amino-2-oxo-4-phenylbutyl]methylamino]carbonyl]-L-proline,phenylmethyl ester (3.6 g., 8.0 mmole) and p-nitrophenyl chloroformate(1.6 g., 8.0 mmole) in methylene chloride (30 ml.). The resultingmixture is stirred for 15 more minutes in the cold bath and 20 minutesafter removal of the bath. The mixture is washed with water (2×), 1Nhydrochloric acid, 10% sodium bicarbonate (4×), and 1N hydrochloricacid. The organic layer is dried (MgSO₄) and concentrated to a red oil.The crude material is filtered through silica gel using chloroform andchloroform:ethyl acetate (1:1) as eluants. Fractions containing thedesired product (R_(f) =0.57, ethyl acetate) are combined andconcentrated. The residue is dissolved in methanol and cooled. Crystalsare filtered off and the filtrate is concentrated to give 2.95 g. of1-[[[(S)-3-[[(4-nitrophenoxy)carbonyl]amino]-2-oxo-4-phenylbutyl]methylamino]carbonyl]-L-proline,phenylmethyl ester as a yellow oil.

(g)1-[[Methyl[(S)-2-oxo-4-phenyl-3-[(1-piperidinylcarbonyl)amino]butyl]amino]carbonyl]-L-proline,phenylmethyl ester

A solution of piperidine (0.5 ml., 5.2 mmole) in toluene (15 ml.) isadded dropwise over five minutes to a cooled solution (0°) of1-[[[(S)-3-[[(4-nitrophenoxy)carbonyl]amino]-2-oxo-4-phenylbutyl]methylamino]carbonyl]-L-proline,phenylmethyl ester (1.48 g., 2.6 mmole) in toluene (40 ml.) in an icebath. The solution immediately turns yellow. The resulting solution isstirred at room temperature for 30 minutes, diluted with water andwashed sequentially with 1N hydrochloric acid, 10% sodium bicarbonate,and water. The organic layer is dried (MgSO₄) and concentrated. Theresidue (1.5 g.) is chromatographed on LPS-1 silica gel using an elutiongradient of 50→100% ethyl acetate in hexane. Fractions containing thedesired product (R_(f) =0.54 traces at R_(f) =0.4, 0.6, ethyl acetate)are combined and concentrated to a yellow oil (0.85 g.). The residue isthen purified by preparative layer chromatography using ethyl acetate aseluant to give 0.81 g. of1-[[methyl[(S)-2-oxo-4-phenyl-3-[(1-piperidinylcarbonyl)amino]butyl]amino]carbonyl]-L-proline,phenylmethyl ester as a pale yellow oil.

(h)1-[[Methyl[(S)-2-oxo-4-phenyl-3-[(1-piperidinylcarbonyl)amino]butyl]amino]carbonyl]-L-proline

A suspension of the phenylmethyl ester product from part (g) (0.8 g.,1.5 mmole) in methanol and palladium hydroxide (20% on carbon) ishydrogenated at room temperature and atmospheric pressure for 30minutes. The mixture is filtered, the solids are rinsed with methanol,and the filtrate is concentrated to give 0.42 g. of yellow oil. Theresidue is chromatographed on LPS-1 silica gel using an elution gradientof 3→10% acetic acid in chloroform. Fractions containing the desiredmaterial are combined and concentrated. The residue is dissolved inmethanol/water, filtered, concentrated (methanol removed) andlyophilized to give a white solid. The material is rechromatographed onCC-4 silica gel using ethyl acetate as the eluant. Fractions containingthe desired produced are combined and lyophilized from water/dioxane togive1-[[methyl[(S)-2-oxo-4-phenyl-3-[(1-piperidinylcarbonyl)amino]butyl]amino]carbonyl]-L-prolineas a white solid; m.p. 69°-72°; [α]_(D) ²⁵ =-37° (c=0.2, methanol). TLC(silica gel; toluene:acetic acid, 4:1) R_(f) =0.18.

Anal. calc'd. for C₂₃ H₃₂ N₄ O₅.1H₂ O: C, 59.72; H, 7.41; N, 12.11.Found: C, 59.86; H, 7.07; N, 11.67.

EXAMPLE 21-[[Methyl[(S)-3-[(4-morpholinylcarbonyl)amino]-2-oxo-4-phenylbutyl]amino]carbonyl]-L-proline(a)1-[[Methyl[(S)-3-[(4-morpholinylcarbonyl)amino]-2-oxo-4-phenylbutyl]amino]carbonyl]-L-proline,phenylmethyl ester

Morpholine (1 ml., 11.4 mmole) is added to a stirring solution of1-[[[(S)-3-[[(4-nitrophenoxy)carbonyl]amino]-2-oxo-4-phenylbutyl]methylamino]carbonyl]-L-proline,phenylmethyl ester (0.9 g., 1.58 mmole) in toluene at 0° in one portion.The reaction mixture turns yellow in 15 minutes and TLC indicatescomplete loss of starting material after 30 minutes. The resultingsolution is washed sequentially with water, 1N hydrochloric acid, and10% sodium bicarbonate. The organic layer is dried (MgSO₄) andconcentrated. The crude product is purified by preparative layerchromatography to give 0.26 g. of1-[[methyl[(S)-3-[(4-morpholinylcarbonyl)amino]carbonyl]-2-oxo-4-phenylbutyl]amino]carbonyl]-L-proline,phenylmethyl ester as a yellow oil. TLC (ethyl acetate) R_(f) =0.18.

(b)1-[[Methyl[(S)-3-[(4-morpholinylcarbonyl)amino]-2-oxo-4-phenylbutyl]amino]carbonyl]-L-proline

A solution of the phenylmethyl ester product from part (a) (0.26 g.,0.48 mmole) in methanol containing palladium hydroxide on carbon ishydrogenated at room temperature and atmospheric pressure for 30minutes. The mixture is filtered (Celite), the solids rinsed withmethanol, and the filtrate is concentrated. The residue is trituratedwith ether and dried under vacuum to give 0.16 g. of1-[[methyl[(S)-3-[(4-morpholinylcarbonyl)amino]-2-oxo-4-phenylbutyl]amino]carbonyl]-L-prolineas a white solid; m.p. 75°-90°; [α]_(D) =-38° (c=0.9, methanol). TLC(silica gel; chloroform:methanol:acetic acid, 4:1:1) R_(f) =0.8, traceat R_(f) =0.2.

Anal. calc'd. for C₂₂ H₃₀ N₄ O₆.0.71H₂ O: C, 57.54; H, 6.89; N, 12.20.Found: C, 57.54; H, 6.78; N, 11.97.

EXAMPLE 31-[[[(S)-3-[[(Cylohexylamino)carbonyl]amino]-2-oxo-4-phenylbutyl]methylamino]carbonyl]-L-proline(a)1-[[[(S)-3-[[((Cyclohexylamino)carbonyl]amino]-2-oxo-4-phenylbutyl]methylamino]carbonyl-L-proline,phenylmethyl ester

Cyclohexylamine (1 ml., 8.7 mmole) is added to a cold (0°) solution of1-[[[(S)-3-[[(4-nitrophenoxy)carbonyl]amino]-2-oxo-4-phenylbutyl]methylamino]carbonyl]-L-proline,phenylmethyl ester (0.9 g., 1.58 mmole) in toluene in one portion. Thesolution turns yellow immediately and TLC indicates all startingmaterial has been consumed. The resulting solution is washedsequentially with water, 1N hydrochloric acid, and 10% sodiumbicarbonate. The organic layer is dried (MgSO₄) and concentrated to apale yellow oil. The crude product is purified (2×) by preparative layerchromatography using ethyl acetate as eluant to give 0.31 g. of1-[[[(S)-3-[[(cyclohexylamino)carbonyl]amino]-2-oxo-4-phenylbutyl]methylamino]carbonyl]-L-proline,phenylmethyl ester as a clear, colorless salt.

(b)1-[[[(S)-3-[[(Cyclohexylamino)carbonyl]amino]-2-oxo-4-phenylbutyl]methylamino]carbonyl]-L-proline

A suspension of the phenylmethyl ester from part (a) (0.31 g., 0.56mmole) in methanol and palladium hydroxide on carbon is hydrogentated atroom temperature and atmospheric pressure for 30 minutes. The resultingmixture is filtered (Celite), the solids washed with methanol, and thefiltrate concentrated to give 0.27 g. of a clear glass. The residue istriturated with ether and dried under vacuum to give 0.175 g. of1-[[[(S)-3-[[(cyclohexylamino)carbonyl]amino]-2-oxo-4-phenylbutyl]methylamino]carbonyl]-L-proline;m.p. 75°-110°; [α]_(D) =27° (c=1, methanol). TLC (silica gel;toluene:acetic acid, 4:1) R_(f) =0.18.

Anal. calc'd. for C₂₄ H₃₄ N₄ O₅.0.8H₂ O: C, 60.93; H, 7.59; N, 11.84.Found: C, 60.93; H, 7.40; N, 11.89.

EXAMPLE 41-[[Methyl[(S)-3-[[(4-methyl-1-piperazinyl)carbonyl]amino]-2-oxo-4-phenylbutyl]amino]carbonyl]-L-proline,dihydrochloride (a)1-[[Methyl[(S)-3-[[(4-methyl-1-piperazinyl)carbonyl]amino]-2-oxo-4-phenylbutyl]amino]carbonyl]-L-proline,phenylmethyl ester

N-Methyl piperazine (1 ml., 9.0 mmole) is added to a cooled (0°)solution of1-[[[(S)-3-[[(4-nitrophenoxy)carbonyl]amino]-2-oxo-4-phenylbutyl]methylamino]carbonyl]-L-proline,phenylmethyl ester (1.06 g., 1.8 mmole) in toluene (20 ml.) in an icebath in one portion. The resulting solution is stirred for an additional45 minutes as it warms to room temperature. The solution is washedsequentially with water and 10% sodium bicarbonate, dried (MgSO₄), andconcentrated. The crude product is chromatographed on LPS-1 silica geleluting with a solution of ethyl acetate:pyridine:acetic acid:water(300:20:6:11→100:20:6:11). Fractions containing the desired product arecombined and concentrated to give 0.3 g. of1-[[methyl[(S)-3-[[(4-methyl-1-piperazinyl)carbonyl]amino]-2-oxo-4-phenylbutyl]amino]carbonyl]-L-proline,phenylmethyl ester; TLC (silica gel; ethyl acetate:pyridine:aceticacid:water, 100:20:6:11) R_(f) =0.26.

(b)1-[[Methyl[(S)-3-[[(4-methyl-1-piperazinyl)carbonyl]amino]-2-oxo-4-phenylbutyl]amino]carbonyl]-L-proline,dihydrochloride

A solution of the phenylmethyl ester product from part (a) (0.3 g., 0.54mmole) in methanol (20 ml.) is hydrogenated for one hour at roomtemperature and atmospheric pressure using palladium hydroxide ascatalyst. The resulting mixture is filtered and concentrated to a yellowoil. The crude product is dissolved in water and washed with ether,ethyl acetate, and chloroform. The aqueous layer is treated with 1Nhydrochloric acid (0.5 ml.) and chromatographed on HP-20 using a 0.01Nhydrochloric acid:methanol (100→0%) gradient. Fractions containing thedesired product are combined, concentrated and lyophilized to give 0.042g. of1-[[methyl[(S)-3-[[(4-methyl-1-piperazinyl)carbonyl]amino]-2-oxo-4-phenylbutyl]amino]carbonyl]-L-proline,dihydrochloride as a bright yellow solid; m.p. (95) 101°-106°; [α]_(D)=-16° (c=0.4, methanol). TLC (silica gel; n-butanol:aceticacid:water:ethyl acetate, 1:1:1:1) R_(f) =0.37.

Anal. calc'd. for C₂₃ H₃₃ N₅ O₅.2HCl.1.7H₂ O: C, 49.06; H, 6.87; N,12.44; Cl, 12.59. Found: C, 49.02; H, 7.08; N, 12.29; Cl, 12.37.

EXAMPLE 51-[[[(S)-3-[[(Dimethylamino)carbonyl]amino]-2-oxo-4-phenylbutyl]methylamino]carbonyl-L-proline(a)1-[[[(S)-3-[[(Dimethylamino)carbonyl]amino]-2-oxo-4-phenylbutyl]methylamino]carbonyl]-L-proline,phenylmethy ester

Diisopropylethylamine (1.5 ml., 8.75 mmole) is added to a cooled (0°)solution of1-[[[(S)-3-[[(4-nitrophenoxy)carbonyl]amino]-2-oxo-4-phenylbutyl]methylamino]carbonyl]-L-proline,phenylmethyl ester (1.0 g., 1.75 mmole) and dimethylamine hydrochloride(0.71 g., 8.75 mmoles) in toluene (50 ml.) in one portion. The resultingyellow solution is stirred in a closed system at 0° for 4 hours and for2 hours following removal of the ice bath. The resulting mixture iswashed sequentially with water, 10% sodium bicarbonate, 1N hydrochloricacid, and 10% sodium bicarbonate. The solution is dried (MgSO₄) andconcentrated to a pale yellow oil which is chromatographed on LPS-1silica gel using 50→100% ethyl acetate in hexane as eluant. Fractionscontaining the desired product are combined and concentrated to give0.68 g. of1-[[[(S)-3-[[(dimethylamino)carbonyl]amino]-2-oxo-4-phenylbutyl]methylamino]carbonyl]-L-proline,phenylmethyl ester as a clear oil. TLC (silica gel, ethyl acetate) R_(f)=0.2.

(b)1-[[[(S)-3-[[(Dimethylamino)carbonyl]amino]-2-oxo-4-phenylbutyl]methylamino]carbonyl]-L-proline

A solution of the phenylmethyl ester product from part (a) (0.68 g.,1.37 mmole) in methanol is hydrogenated at room temperature andatmospheric pressure for three hours using palladium hydroxide on carbonas catalyst. The resulting solution is filtered and concentrated to awhite foam which is lyophilized from dioxane/water to give 0.5 g. of1-[[[(S)-3-[[(dimethylamino)carbonyl]amino]-2-oxo-4-phenylbutyl]methylamino]carbonyl]-L-proline;m.p. (60) 74°-104°; [α]_(D) =-38.6° (c=1.0, methanol). TLC (silica gel;chloroform:methanol:acetic acid, 4:1:1) R_(f) =0.73, trace at 0.33.

Anal. calc'd. for C₂₂ H₂₈ N₄ O₅.1.1H₂ O: C, 56.62; H, 7.17; N, 13.20.Found: C, 56.63; H, 7.25; N, 13.14.

EXAMPLES 6-30

Following the procedure of Examples 1-5, the amine shown in Col. I istreated with 4-nitrophenyl chloroformate and then reacted with the amineshown in Col. II to yield the ester product shown in Col. III. Removalof the R₆ ester group yields the corresponding acid product.

      Col. I Col. II Col. III      ##STR61##      ##STR62##      ##STR63##           Example R.sub.3     ##STR64##      R X       6      ##STR65##      NH.sub.2 CH.sub.3      ##STR66##      7     ##STR67##      NHCH.sub.3 CH.sub.3      ##STR68##      8     ##STR69##      N(C.sub.2      H.sub.5).sub.2 CH.sub.3     ##STR70##      9     ##STR71##      ##STR72##      CH.sub.3      ##STR73##      10     ##STR74##      ##STR75##      CH.sub.3      ##STR76##      11     ##STR77##      ##STR78##      CH.sub.3      ##STR79##      12     ##STR80##      ##STR81##      CH.sub.3      ##STR82##      13     ##STR83##      ##STR84##      CH.sub.3      ##STR85##       14 H.sub.5 C.sub.2H.sub.2      C     ##STR86##      CH.sub.3      ##STR87##      15     ##STR88##      ##STR89##      CH.sub.3      ##STR90##      16     ##STR91##      ##STR92##      CH.sub.3      ##STR93##      17     ##STR94##      ##STR95##      CH.sub.3      ##STR96##      18     ##STR97##      ##STR98##      CH.sub.3      ##STR99##      19     ##STR100##      ##STR101##      ##STR102##      ##STR103##      20     ##STR104##      ##STR105##      ##STR106##      ##STR107##      21     ##STR108##      ##STR109##      ##STR110##      ##STR111##      22     ##STR112##      ##STR113##      ##STR114##      ##STR115##      23     ##STR116##      ##STR117##      CH.sub.3      ##STR118##      24     ##STR119##      ##STR120##      CH.sub.3      ##STR121##      25     ##STR122##      ##STR123##      CH.sub.3      ##STR124##      26     ##STR125##      N(CH.sub.3).sub.2 CH.sub.3      ##STR126##      27     ##STR127##      ##STR128##      CH.sub.3      ##STR129##      28     ##STR130##      ##STR131##      CH.sub.3      ##STR132##      29     ##STR133##      ##STR134##      CH.sub.3      ##STR135##      30     ##STR136##      ##STR137##      CH.sub.3      ##STR138##

The R₃ protecting group shown in Example 17, the R₁ protecting groupsshown in Examples 15 and 16, the R protecting groups shown in Examples21 and 22, the R₅ protecting group shown in Example 27, and the R₂₆protecting group shown in Example 19 are removed as the last step in thesynthesis. The R₆ ester groups shown in Examples 28 to 30 are notremoved.

EXAMPLE 31

1000 tablets each containing the following ingredients:

    ______________________________________    1-[[Methyl[(S)--2-oxo-4-phenyl-3-                          100 mg.    [(1-piperidinylcarbonyl)amino]-    butyl]amino]carbonyl]-L-proline    Cornstarch             50 mg.    Gelatin                7.5 mg.    Avicel(microcrystalline cellulose)                           25 mg.    Magnesium stearate     2.5 mg.                          185 mg.    ______________________________________

are prepared from sufficient bulk quantities by mixing the1-[[methyl[(S)-2-oxo-4-phenyl-3-[(1-piperidinylcarbonyl)amino]butyl]amino]carbonyl]-L-prolineand cornstarch with an aqueous solution of the gelatin. The mixture isdried and ground to a fine powder. The Avicel and then the magnesiumstearate are admixed with granulation. This mixture is then compressedin a tablet press to form 1000 tablets each containing 100 mg. of activeingredient.

In a similar manner, tablets containing 100 mg. of the product of any ofExamples 2 to 30 can be prepared.

A similar procedure can be employed to form tablets containing 50 mg. ofactive ingredient.

EXAMPLE 32

Two piece #1 gelatin capsules are filled with a mixture of the followingingredients:

    ______________________________________    1-[[Methyl[(S)--3-[(4-morpholinyl-                           50 mg.    carbonyl)amino]-2-oxo-4-phenyl-    butyl]amino]carbonyl]-L-proline    Magnesium stearate     7 mg.    Lactose               193 mg.                          250 mg.    ______________________________________

In a similar manner capsules containing 50 mg. of the product of any ofExamples 1 and 3 to 30 can be prepared.

EXAMPLE 33

An injectable solution is prepared as follows:

    ______________________________________    1-[[[(S)--3-[[(Cyclohexylamino)-                              500    g.    carbonyl]amino]-2-oxo-4-phenyl-    butyl]methylamino]carbonyl]-L-proline    Methyl paraben            5      g.    Propyl paraben            1      g.    Sodium chloride           25     g.    Water for injection       5      l.    ______________________________________

The active substance, preservatives and sodium chloride are dissolved in3 liters of water for injection and then the volume is brought up to 5liters. The solution is filtered through a sterile filter andaseptically filled into presterilized vials which are closed withpresterilized rubber closures. Each vial contains 5 ml. of solution in aconcentration of 100 mg. of active ingredient per ml. of solution forinjection.

In a similar manner, an injectable solution containing 100 mg. of activeingredient per ml. of solution can be prepared for the product of any ofExamples 1, 2 and 4 to 30.

EXAMPLE 34

1000 tablets containing the following ingredients:

    ______________________________________    1-[[[(S)--3-[[(Dimethylamino)-                         100 mg.    carbonyl]amino]-2-oxo-4-phenyl-    butyl]methylamino]carbonyl]-L-    proline    Avicel               100 mg.    Hydrochlorothiazide  12.5 mg.    Lactose              113 mg.    Cornstarch           17.5 mg.    Stearic acid          7 mg.                         250 mg.    ______________________________________

are prepared from sufficient bulk quantities by slugging the1-[[[(S)-3-[[(dimethylamino)carbonyl]amino]-2-oxo-4-phenylbutyl]methylamino]carbonyl]-L-proline,Avicel, and a portion of the stearic acid. The slugs are ground andpassed through a #2 screen, then mixed with the hydrochlorothiazide,lactose, cornstarch, and remainder of the stearic acid. The mixture iscompressed into 350 mg. capsule shaped tablets in a tablet press. Thetablets are scored for dividing in half.

In similar manner, tablets can be prepared containing 100 mg. of theproduct of any of Examples 1 to 4 and 6 to 30.

What is claimed is:
 1. A compound of the formula ##STR139## including apharmaceutically acceptable salt thereof wherein: X is ##STR140## R₇ ishydrogen, lower alkyl, halogen, hydroxy, ##STR141## a 1- or 2-naphthylof the formula ##STR142## a substituted 1- or 2-naphthyl of the formula##STR143## a 1- or 2-naphthyloxy of the formula ##STR144## substituted1- or 2-naphthyloxy of the formula ##STR145## a 1- or 2-naphthylthio ofthe formula ##STR146## or a substituted 1- or 2-naphthylthio of theformula ##STR147## R₈ is halogen, ##STR148## -O-lower alkyl, a 1- or2-naphthyloxy of the formula ##STR149## a substituted 1- or2-naphthyloxy of the formula ##STR150## a 1- or 2-naphthylthio of theformula ##STR151## or a substituted 1- or 2-naphthylthio of the formula##STR152## R₉ is keto, ##STR153## R₁₀ is halogen or --Y--R₁₆ ; R₁₃ islower alkyl of 1 to 4 carbons, lower alkoxy of 1 to 4 carbons, loweralkylthio of 1 to 4 carbons, chloro, bromo, fluoro, trifluoromethyl,hydroxy, phenyl, phenoxy, phenylthio, or phenylmethyl;R₁₄ is lower alkylof 1 to 4 carbons, lower alkoxy of 1 to 4 carbons, lower alkylthio of 1to 4 carbons, chloro, bromo, fluoro, trifluoromethyl or hydroxy; m iszero, one, two, three, or four; p is one, two or three provided that pis more than one only if R₁₃ or R₁₄ is methyl, methoxy, chloro, orfluoro; R₁₅ is hydrogen or lower alkyl of 1 to 4 carbons; Y is oxygen orsulfur; R₁₆ is lower alkyl of 1 to 4 carbons, ##STR154## r is an integerfrom 1 to 4; R₁₉ is lower alkyl, benzyl or phenethyl; R₂₀ is hydrogen,lower alkyl, benzyl or phenethyl; R is hydrogen, lower alkyl, halosubstituted lower alkyl, ##STR155## R₁ and R₂ are independently selectedfrom the group consisting of hydrogen, lower alkyl, halo substitutedlower alkyl, ##STR156## v is an integer from 2 to 6; R₃ is hydrogen,lower alkyl, ##STR157## halo substituted lower alkyl, ##STR158## R₆ ishydrogen, lower alkyl, benzyl, benzhydryl, ##STR159## R₁₇ is hydrogen,lower alkyl, cycloalkyl or phenyl; R₁₈ is hydrogen, lower alkyl, loweralkoxy or phenyl; R₂₁ and R₂₂ are independently selected from the groupconsisting of hydrogen and lower alkyl; and R₂₃ is lower alkyl.
 2. Acompound of claim 1 wherein:X is ##STR160## R₆ is hydrogen or an alkalimetal salt ion; R₇ is hydrogen, cyclohexyl, lower alkoxy of 1 to 4carbons, ##STR161## m is zero, one or two; and R₁₃ is methyl, methoxy,methylthio, chloro, bromo, fluoro, or hydroxy.
 3. A compound of claim 2whereinR is straight or branched chain lower alkyl of 1 to 4 carbons; R₁and R₂ are independently selected from straight or branched chain loweralkyl of 1 to 4 carbons, or R₁ is cyclohexyl and R₂ is hydrogen; R₃ isstraight or branched chain lower alkyl of 1 to 4 carbons, ##STR162## mis zero, one, or two; and R₁₄ is methyl, methoxy, methylthio, Cl, Br, F,or hydroxy.
 4. A compound of claim 3 wherein:X is ##STR163## R ismethyl; and R₆ is hydrogen or an alkali metal salt ion.
 5. A compound ofclaim 4 wherein:R₁ is cyclohexyl and R₂ is hydrogen.
 6. The compound ofclaim 5,1-[[[(S)-3-[[(cyclohexylamino)carbonyl]amino]-2-oxo-4-phenylbutyl]methylamino]carbonyl]-L-proline.7. A compound of claim 4 whereinR₁ and R₂ are both methyl.
 8. Thecompound of claim 7,1-[[[(S)-3-[[(dimethylamino)carbonyl]amino]-2-oxo-4-phenylbutyl]methylamino]carbonyl]-L-proline.9. A pharmaceutical composition useful for treating hypertensioncomprising a pharmaceutically acceptable carrier and a hypotensivecompound of the formula ##STR164## wherein R, R₁, R₂, R₃ and X are asdefined in claim 1.